Electric switch



Dec. 14, 1943. J. E. LAKE ELECTRIC SWITCH Filed Feb. 28, 1942 Inventon John E. LaKe, by W (5 AMA His Attorney Patented Dee. 14, 1943 ELECTRIC swrrcn John E. Lake, Schenectady," N. Y., might.- to

General Electric New York Company a corporation of Application February 28, 1342, Serial No. 432,724

2 Claims.

My invention relates to electric switches, more particularly to electric switchesof the type known as contactors, and has for its object a simple and reliable device of this character, the

movable parts of which are constructed so as to balance impact forces and prevent circuit failure connected to a bell crank arm or lever, the opposite ends of the levers being pivotally connected together. These bell cranks are mechanically connected through a link to the switch arm for operation of the switch arm to a closed circuit position when the magnet is energized.

For a more complete understanding of my invention, reference should be had to the accompanying drawing in which Fig. 1 is a plan view of an electric switch. embodying my invention; Fig. 2 is a left-hand elevation view of Fig. 1; Fig. 3 is a sectional view taken along the line 33 of Fig. 1 and looking in the direction of the arrows; whileFig. 4 is a simplified view in perspective of the device shown in Figs. 1 to 3, inclusive.

Referring to the drawing, my invention in one form comprises a base plate or member II! which may e made of metal and which forms a support for the various parts of the device. These parts comprise a contact arm I I made of electri= cally; insulating material and provided with a central pivotal support I2, a stationary contact and terminal support I3 made of electrically insulating material secured to the base adjacent the upper end of the contact arm as seen in Figs.

1, 2 ands, a stationary contact and terminal support I4 alsosecured to the baseadjacent the other end of the pivoted contact arm II, anda magnet coil I5 between and operating bell cranks i6 and I! which are connected to the switch arm I I. Thus the coil I5 operates to move the switch arm II about its pivot I2 between its open and closed circuit positions. I

For the support of the stationary pivot rod I2,

brackets I8 and I9 areprovided at its opposite The bracket I9 iur-' 23, the outer side plates 24 and-25 of which are secured to the horizontal portion 22 by suitable screws 26 and 21.

Preferably, the contact arm II is loosely mounted on the pivot rod I2 so that it turns on the rod in moving between its closed and open circuit positions. on the rod by means of compression springs 28 and 29 on opposite sides, the spring 28 being between the contact arm and the bracket I8; while spring 29 is between the contact arm and a clip 30 frictionally secured to the rod I2. k

The contact arm II, which together with the supports I3 and I4 is preferably made of a molded electrically insulating material such as a phenolic condensation product, is of irregular shape to provide for are barriers between contacts and for convenience in the connection of the operating mechanism. At its upper end, as

seen in Figs. 1 to 3, it carries two spring pressed bridging contacts 3| and 32 which are spaced apart and engage respectively pairs of stationary contacts 33 and 34 (one contact of the pair 34 not being shown) mounted on the support I3.

An arc barrier wall 35 formed 'ntegrally with the support i3 extends upward bet een the pairs of stationary contacts 33 and 34 and the upper end of the switch arm II has a curved or hood portion 33 between the movabiebridging arms'3i and 32 and partially enclosing and encircling the barrier 35 when the contact arm is in its closed circuit position. This provides an arc path through the air of increased length between the bridging contacts when they are in the closed circuit position. It will be understood that these bridging contacts serve electrically to connect together the contacts of each of the pairs 33 and 34 and, therefore, the bridging contacts are connected to an electric circuit only after being moved toward their closed circuit positions.

' At its other or lower end the contact arm II is provided with a third bridging contact 31 which, when the contact arm is moved counterclockwise, as seen in Fig. 2, engages stationary contacts secured on the ends of electrically conducting supports 38 and 39 secured to the electrically insulating support I4. Also'carried on this lower end of the contact arm is an interlock or control circuit bridging contact 40 which, when the contact arm is moved to its closed circuit position, engages two stationary contacts H and 42 mounted on the support I4. Also con- .tacts 40, and 42 can be assembled reversed with respect to the position shown so that they are normally closed when arm I] is in the open It is held in a central position jars of translation applied to the support on which the switch is mounted.

For the operation of the contact arm II, the magnet coil I is provided with two aligned plunger armatures 43 and 44, these armatures extending substantially parallel with the base H1. The outer ends of these armatures are pivotally connected respectively to the ends of the bell crank levers l6 and I1 pivotally mounted on the base In. As shown, the bell crank lever lBis pivotally mounted at its center on the pivot pin l2, while the bell crank lever H is pivoted at its center also on a pivot pin 45 (Fig.2) secured to the bracket l9. Thus it will be observed that the arms of the bell cranks to which the armatures are attached extend upward from the base in substantially parallel relation with each other.

and substantially at rightangles to the center line of the coil IS. The other two arms of the bell cranks extend toward each other into overlapping relation and they are connected pivotally together by pivot pin46. Enough looseness in a radial direction is provided between the pin 46 and at least one of the bell cranks to permit sufficient pivotal movement of the bell cranks to move the plungers between their at-,

tracted and unattracted positions. One of the bell cranks, as shown the bell crank i7, is connected to the switch arm H by means of a link ill having one end pivotally connected to the link ll at the point 48 and the other end pivotally connected to the switch arm at the point 49.

A helical spring 50 is provided for biasing the contact arm to the open position shown. This spring surrounds a hub 5! on the contact arm surrounding the pin I2. is secured to the base Ill, while the other end 52 is secured to the switch arm so as to bias the switch arm to its open circuit position.

When the coil I5 is energized, the two plungers 43 and 44 are attracted toward each other and preferably engage each other at their inner ends. The twoplungers are connected to each other through the pivot 46 and operate through the link 41 the contact arm to its closed circuit position.

It will be observed that the movable magnet One end of the spring operating parts, including the two plungers of identical construction and weight and the two identical bell cranks, provide a construction which is dynamically balanced with respect to shocks and jars of translation or straight line movement applied to the support on which the switch is mounted.

For example, a translational shock applied to the switch in a direction from top to bottom as viewed in Fig. 2, which force is applied directlyto the supporting pivots I2 and 45, produces a force due to the inertia of the parts tending to'turn the bell crankLIG in a counterclockwise direction about the pivot l2. This same shock also produces a force tending to turn the bell crank I! in a clockwise direction about the pivot 45. Since these two forces counteract each other at the pivot 46 and are equal, the tendency of the bell cranks to turn is balanced out.

Likewise equal and opposite forces are produced by a shock in the opposite direction.

The plunger type armatures43 and 44 are advantageous in eliminating rebound of the armatures from their attracted positions in the event of a shock. Thu an armature which in its attracted position is in solid'abutting engagement with a cooperating magnet frame secured rigidly to a support, maybe thrown from its attracted position against the pull of the magnet coil by a severe shock. This is because the shock is applied through the support directly to the stationary magnet frame and when transmitted by the magnet frame to the armature may throw the armature toward its unattracted position against the holding force of the magnet coil. In the arrangement I have disclosed, the two plunger type armatures engage each other at their inner ends when in their attracted positions, and therefore do not abuttingly engage the magnet frame 23. Shocks applied to the magnet frame in the direction of movement of the plunger armatures, therefore, are not transmitted directly from the magnet frame to the plungers, and this rebound movement of one or the other of the plungers is avoided.

A translational shock applied to the switch from the left-to the right, as viewed in 'Fig. 2, does not produce forces tending to move the bell cranks to their open positionsbecause of the fact that the bell cranks are damped by the much greater inertia forces of the plunger armatures 43 and-44 which are not free to move in that direction. This is true also of the force of a shock in the opposite direction. Also, a shock at right angles. to the device, as seen in Fig. 2, does not produce any switch opening force because the parts are not free to move in that direction.

Also shown on the drawing are the various quickly detachable terminal connections for the stationary contacts. Thus the screw connections 53 and 54 lead respectively to the pair of stationary contacts 33, while in a similar manner the screw connections 55 and 56 lead respectively to the pair of contacts 34. Likewise, the stationary contact 4| is provided with a contact screw 51, the stationary contact 42 with a contact screw 58, and the supports 38 and 39 with contact screws 59 and 60.

It is contemplated that the electric switch disclosed will be used in a 3-phase supply circuit such as for the starting of a 3-phase electric motor. Thus the three pairs of main contacts 33, 34, 38 and 39 will be connected in the three supply lines to the electric motor. The auxiliary interlock bridging contact 40 will be connected in any suitable control circuit that may be desired, for example, to short-circuit a push button switch initially used to close the circuit of the coil l5.

The bridging contacts 3|, 32 and 31 are suitably connected resiliently to the arm ll. The

support for they bridging contact 3| will be described in detail, the supports for th other bridglng contacts being the same. It consists of a U-shaped metal strap ,6! whose arms are spaced apart a distance slightly greater than thewidth aperture lying between the to hold the U-shaped member in position.- Preferably. these projections '64 and 65 are made by striking out slight tabs of the metal of the arms. When the U-shaped member is put in position, two arms are pressed together somewhat, the member being made of resilient material so that the outer projection 65 in each arm passes through the aperture 63. 'Then the arms spring apart with the two opposite side walls of the pairs of projections on the arms.

' Preferably also, as seen in Fig. 2, the bridging contact 3|, as well as the other bridging con-- tacts, is positioned angularly with respect to its pair of stationary contacts 33 so that one end of the bridging member engages its stationary contact first and after relatively small angular movement of the arm [I toward the closed circuit position. As shown, engagement is made first with the lowermost contact This is or adeach other and second arms of said levers extending in substantially parallel relation with each other, a pivotal connection between said first arms, a magnet coil'mounted between said second arms, a pair of plunger armatures extending into opposite ends of said coil connected to said second arms. said plunger armatures extending into opposite ends of'said coil and having their inner ends in abutting engagement with each other when moved to their attracted positions upon energization of said coil, a switch arm pivotally mounted at its center, a link connecting said switch arm with one of said levers, and a spring for biasing said switch arm about its pivot to open circuit position whereby said arma'. tures are biased apart to unattracted positions and upon energization of said coil said armatures are pulled toward each other and said switch arm thereby turned to its closed circuit position.

2. An electric switch comprising two bell crank levers mounted on spaced apart stationary pivots with first arms of said levers extending toward each other and second arms of said levers extending in substantially parallel relation .with

each other, a pivotal connection between the ends of said first arms, a magnet coil mounted v between said second arms, a pair of plunger vantage during the opening movement in that the opening of the circuit and any arcing takes place at the upper contacts.

While I have shown a particular embodiment of my invention, it will be understood, of course, that I do not wish to be limited thereto since many modifications may be made, and I therefore contemplate by the appended claims to cover any such modifications as fall within spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent 01. the United States is:

, 1. An electric. switch comprising two bell crank levers mounted on spaced apart stationary pivots with first arms or said levers-extending toward the true armatures in said coil having their outer ends pivotally connected to the ends of said second arms, a switch arm mounted at its center on a stationary pivot, a switch contact carried on each end of 'said arm, said plunger armatures extending into opposite ends of said coil and having their innerv ends in abutting engagement with each other when moved to their attracted positions upon energization of said coil, a link connecting said switch arm with one of said levers, and a spring for biasing said switch arm about its pivot to open circuit position whereby said plungers are. biased apart to unattracted positions and upon energization of said coil said plun'gers are pulled toward each other thereby 

